The following abbreviations are utilized herein:    3GPP third generation partnership project    ACK acknowledgement    A/N ACK/NACK    ARQ automatic repeat-request    AT allocation table    BS base station    CAZAC constant amplitude zero autocorrelation    CDM code division multiplexing    CQI channel quality indicator    CRC cyclic redundancy check    DFT discrete Fourier transform    DL downlink (Node B to UE)    DTX discontinuous transmission    E-UTRAN evolved universal terrestrial radio access network (LTE)    HARQ hybrid automatic repeat-request    L1 layer 1 (physical layer, PHY)    LTE long term evolution of UTRAN (E-UTRAN)    MIMO multiple input/multiple output    NACK negative acknowledgement    Node B base station    OFDM orthogonal frequency division multiplexed    OFDMA orthogonal frequency division multiple access    PRB physical resource block    RLC radio link control    RS reference signal    SINR signal to interference-plus-noise ratio    SNR signal to noise ratio    TDM time division multiplexed    TTI transmission time interval    UE user equipment, such as a mobile station or mobile terminal    UL uplink (UE to Node B)    UMTS universal mobile telecommunications system    UTRAN universal terrestrial radio access network
A proposed communication system known as E-UTRAN or LTE is currently under discussion within the 3GPP. The E-UTRAN system is a packet-based system that operates under strict control by the BS (Node B). The usage of physical UL/DL resources is signaled from the Node B to the UE, typically in each TTI. The signaling is realized by use of UL and DL ATs. The UL and DL ATs indicate to the UE which physical resources are assigned for UL and DL data transmissions, respectively. When data transmission occurs over a wireless medium, there is a risk of error when receiving and detecting the data.
From the point of view of the UL, there are a number of potential signaling errors:
(1) The UL allocation fails and only the UL allocation was sent.
(2) The DL allocation fails and only the DL allocation was sent.
(3) Both UL and DL allocations fail.
(4) The DL allocation fails but the UL allocation does not.
(5) The UL allocation fails but the DL allocation does not.
A working assumption in the 3GPP is that the UL and DL ATs are separately encoded (e.g., error (1) or (2)). Error (3) may occur, for example, in the situation where the UL and DL ATs are jointly coded. The error rate related to the resource allocation signaling is assumed to be on the order of 1%-5%.
Note that the ACK/NACK for the data packet that is indicated by the DL AT will likely be associated with a different TTI than the ACK/NACK for the UL AT (e.g., UL data). This is due to the fact that ACK/NACK signaling cannot be transmitted until the corresponding DL data packet has been decoded. This is in contrast to the UL data since the UL data can be transmitted immediately once the UL AT has been correctly received.
It is noted that when a UE fails to decode the UL/DL AT, it does not realize that there was a resource allocation for the UE.
In RAN1 meeting #46bis held in Seoul, some working assumptions related to the UL control signaling were agreed on. Related to the data-non-associated control signal (e.g., ACK/NACK, CQI) transmission in the absence of UL data, the working assumption is to use a reserved frequency and time resource for control signaling (a “shared control resource”). In RAN meeting #47bis held in Sorrento, CDM was agreed on as a working assumption for the multiple access method between UEs simultaneously transmitting only control signaling. It has also been agreed that control and data are multiplexed prior to DFT (e.g., TDM) when both UL data and data-non-associated control signals are present. In that case, the data-non-associated control signals are transmitted with UL data on dedicated resources.